1. Field of the Invention
The present invention relates to a pump and a pump securing device for mounting a pump on a container, which ensure that the pump will operate with consistent dosage accuracy. More specifically, the present invention relates to a low-profile pump and a mounting cup or ferrule which is securely mounted to the pump without crimping, which prevents variations in the dosage size of the pump, and which allows venting of the container.
2. Description of the Prior Art
In the art of container-mounted pumps, it is known to crimp the pump on the neck of the container using a mounting cup or ferrule. Conventionally, it has been required, during a sub-assembly step, to crimp the mounting cup or ferrule to the pump body, so that the resulting assembly can be mounted as a unit to a container neck. In order to ensure proper sealing of the pump on the container, thereby to minimize leakage, it is conventional to use a resilient gasket or gaskets which interact with the container neck and/or the pump housing. A disadvantage of such conventional arrangements is that when the pump is secured to the container by conventional mounting techniques--e.g., crimping--the lower (i.e., axially inner) gasket is often compressed during the crimping process, and the amount of lower gasket compression cannot easily be controlled. As a result, variations in the amount of compression of the lower gasket will cause variations in the stroke length of the pump piston, due to upward pressure on the pump housing caused by the crimped and compressed gasket. This upward pressure on the pump housing can cause reduction in the stroke length of the pump piston in two ways: first, by moving the pump housing upwardly, and second, by causing the upper portion of the pump housing to compress the outer edges of the upper (i.e., axially outer) gasket (also called the diaphragm) and thereby forcing down the central part of the upper gasket, reducing the stroke length of the pump piston. Dosage variations are therefore created during the process of crimping the pump and mounting cup to the container. Such dosage variations, in many uses of container-mounted pumps, are not acceptable.